This chart summarizes the differences
A typical wood-framed residential flooring system is more complicated than you think.
The terms “underlayment” and “subfloor” are often used interchangeably, but they are separate layers.
OSB (oriented strand board) is a different form of sheet material.
The Spruce / Madelyn Goodnight
While the name may be unfamiliar, you probably recognize this material.
The sheets are typically 4 by 8 or 4 by 12 feet in size.
In the 1950s, this material quickly replaced solid wood planking as a home subfloor material.
The spacing of the joists governs the recommended thickness of the plywood subfloor.
However, check with your local code authorities for the official recommendations.
OSB came into use as a subfloor material in the 1970s.
The jot down of OSB used for subfloors generally is made with tongue-and-groove edges (T & G).
The standard subfloor for joists spaced up to 16 inches apart is 23/32-inch T & G sheets.
When looking at the attic or shed flooring, look at a subfloor’s horizontal shear strength.
OSB has twice the horizontal shear strength of plywood.
It’s a better option than plywood for subflooring in attics and sheds.
So, if your shed is prone to dampness and moisture, plywood might be more durable.
OSB
Oriented strand board has many flat wood chips glued up together in a solid sheet.
Overall, plywood is more resistant to permanent swelling.
OSB has untreated edges that are somewhat more susceptible to swelling if they get wet.
Serious spills and flooding should be remedied as soon as possible.
Both plywood and OSB will burn should a house fire break out.
Care and Cleaning
No care and cleaning necessary; this is a hidden building material.
Durability and Maintenance
A well-installed subfloor should last as long as the house itself.
There is no maintenance required, except to keep the subfloor as dry as possible.
Installation
Both subfloor materials are installed the same way.
End joints should be offset from row to row so they don’t line up.
Many installers apply a bead of construction adhesive across each joist before laying the subfloor sheets down.
Where the panels are glued down, OSB also has slightly less holding power with construction adhesives.
Lifespan
Plywood subfloors should last as long as the house itself.
Like plywood, OSB subfloors should last as long as the house itself.
Sizes
Plywood is available in the same sizes as OSB.
OSB comes in the same sizes as plywood subfloor sheets.
However, very few people are able to recognize this.
Rarely, a prospective homeowner may recognize that OSB is the cheaper subfloor material.
